Continuing where Stitch! The Movie left off, Lilo and Stitch are given the task of collecting the rest of Jumba's missing experiments, changing them from bad to good and finding the one place where they truly belong. Meanwhile, the former Captain Gantu and his reluctant partner Experiment 625 try to capture the experiments for the imprisoned Dr. Hämsterviel.
On May 29, 2007, the series moved from its daily 12 p.m. time slot to its daily time slot at 5 and 5:30 a.m. In 2010, the series time slot was lost by Playhouse Disney, which lost it to have Phineas and Ferb episodes one year later, in 2011. The series has been officially released on DVD in Japan and Greece. The series returned on the Disney Junior channel and the Disney Junior block on Disney Channel starting from March 23, 2012, in which the show was removed from the Disney Junior block on Disney Channel on September 30, 2013. Disney Junior continued to air the series until 2014. On March 11, 2018, the series returned on Disney XD, starting with a mini-marathon on that day.
- Main article: List of Lilo & Stitch: The Series episodes
|Season||Ep #||First Airdate||Last Airdate|
|Season 1||39||September 20, 2003||February 28, 2004|
|Season 2||26||November 5, 2004||July 29, 2006|
- X-626/Stitch (voiced by Chris Sanders) - One of the two lead characters, he is Lilo's pet and best friend. After finding out about his 625 other experiment "cousins", he and Lilo set out to find them, reform them to good, and have them join their ever-expanding ʻohana. He also learns more about life on Earth along the way.
- Lilo Pelekai (voiced by Daveigh Chase) - The other lead character, she is Stitch's owner and best friend. She assists Stitch in finding his "cousins", naming them, and finding them a "one true place" where they can use their abilities for good.
- Jumba Jookiba (voiced by David Ogden Stiers) - The creator of the many genetic experiments, which includes Stitch and Reuben, he lives with the Pelekai ʻohana after being exiled to Earth in the original film alongside Pleakley. He plays the role of Lilo and Nani's "uncle" in the ʻohana and wears a human disguise in public. He frequently assists Lilo and Stitch in capturing the experiments, usually by providing them with various tools he creates.
- Wendy Pleakley (voiced by Kevin McDonald) - A former agent for the United Galactic Federation, he lives with the Pelekai ʻohana after being exiled to Earth in the original film alongside Jumba. He plays the role of Lilo and Nani's "aunt" in the ʻohana and frequently cross-dresses in the role. He also assists Lilo and Stitch in capturing the experiments, but to a lesser extent. He normally helps Nani out in maintaining the household. His first name is not revealed until the episode "Fibber".
- Nani Pelekai (voiced by Tia Carrere) - Lilo's older sister and legal guardian, and caretaker of the household that they live in. She is usually busy and stressed out, and frequently has to deal with Lilo and Stitch's antics.
- Mertle Edmonds (voiced by Liliana Mumy) - Lilo's classmate and rival. She appeared in many episodes of the series, usually causing conflicts for the title duo in the episodes she appeared in.
- X-007/Gigi (voiced by Tress MacNeille) - Mertle's pet. Gigi is a Shih-Tzu like experiment and the one place where she truly belongs is with Mertle as her pet.
- X-624/Angel (voiced by Tara Strong) - Stitch's main love interest. Angel is a pink pretty experiment who designed to turn evil the good experiments with a siren song. She was caught by Gantu and rescued in "Snafu". She appeared in only that episode and her eponymous debut, along with a cameo appearance in "Remmy". Her place who truly belongs is with Stitch as his true love.
- X-221/Sparky (voiced by Frank Welker) - The first of Stitch's cousins that Stitch met. Sparky is a yellow experiment designed to create electric energy. His place who truly belongs is in the old lighthouse to use his electric skills to make it light. Appeared in the most episodes of the series.
- David Kawena (voiced by Dee Bradley Baker) - Nani's boyfriend. David is a great surfer. Like Nani, he also has trouble finding employment. He is also one of only five humans (the other four being Nani, Victoria, Cobra Bubbles and later Mertle) who are aware of the aliens.
- Cobra Bubbles (voiced by Kevin Michael Richardson) - Aside from Lilo's family who is aware of the aliens and experiments.
- Yuki, Elena and Teresa - Mertle's possé consists of Yuki (voiced by Lili Ishida), Elena (voiced by Jillian Henry) and Teresa (voiced by Kali Whitehurst). They usually travel in a group and seldom say anything other than a sarcastic "Yeah!" in unison when agreeing with Mertle on something.
- Mrs. Edmonds - (voiced by Tia Carrere) Mertle's mother.
- Grand Councilwoman (voiced by Zoe Caldwell) - the leader of the Galaxy's ruling Federation, she is the one who banished Stitch in the first movie. She later agrees to let Lilo and Stitch become official experiment hunters in order to retrieve all of the remaining experiments. She appeared in only one episode of the series ("Finder").
- Keoni Jameson (voiced by Shaun Fleming) - Keoni is a young, laid-back boy on whom Lilo has a crush. Lilo constantly tries to vie for his affections. He had a crush on Pleakley, whom he knows as Lilo's "aunt", in the episode "Hunkahunka", but in "Nosy" he stated that he only had the crush for that one week. His father owns several businesses on Kauai. He has a friend who just happens to be a girl (not a girlfriend, though). This friend is first shown in "Hunkahunka" and later seen in "Morpholomew".
- Mr. Jameson - Mr. Jameson is the father of Keoni and, on several occasions, Nani's employer. He owns several businesses around Kauai, including the Birds of Paradise Hotel.
- Moses Puloki (voiced by Kunewa Mook) - The hula teacher of Lilo's school, where he teaches Lilo, Victoria, Mertle, Yuki, Elena, and Teresa how to hula. He is very patient with his students and tolerates their antics. Lilo and her ex-friends often call Moses "Kumu" (Hawaiian for teacher).
- Officer Kahiko - Officer Kahiko is a police officer who knows Lilo well and occasionally tries to keep her out of trouble when she isn't accompanied by Nani. He appears in the episodes "Holio", "Bonnie & Clyde", "Snooty", and "Shush".
- Victoria (voiced by Alyson Stoner) - Lilo's new (human) best friend, whom she meets in the episode "Swapper". Throughout the episode, Lilo tries to prove to her she wasn't weird. But in the end, Victoria reveals she likes weird stuff so she and Lilo become best friends. Victoria is also in Lilo's Hula Class and owns Snooty (Experiment 277) as a pet. She appears in the episodes "Swapper", "Snooty", "Slick", "Remmy", and "Wishy-Washy".
- Mrs. Hasagawa (voiced by Amy Hill) - The little old lady who owns the fruit stand. Several experiments live with her.
- Sunburned Ice Cream Tourist (voiced by Frank Welker) - This is a running gag throughout the Lilo & Stitch franchise. Whenever he appears, the Sunburned Ice Cream Tourist drops his ice cream (presumably a mint-flavored ice cream from its color) from its cone before he can finish it. The Sunburned Ice Cream Tourist never has a spoken part in the series except saying, "Whoa!" when he tripped over a pod. He also cries after suffering from 151 (Babyfier)'s effects. His real eyes can be seen in "Swirly". This gag was also seen in a Season 2 episode of Phineas and Ferb: "I Was a Middle Aged Robot" with The Ballpit Kid.
- Luki (voiced by Derek Stephen Prince) - A man who owns a shave ice store and a few shaved ice carts and is usually a background character. Both Slushy and Dupe work for him.
- Charles and Mary - A honeymooning couple who came to Kauai to relax and have fun, but often face trouble with Stitch's cousins.
- Jacques von Hämsterviel (voiced by Jeff Bennett) - He is Jumba's former lab partner who seeks to capture the genetic experiments he helped to create through financing, hiring Gantu for help. He works from his "prison cell", which he set up as a laboratory. His name is usually mispronounced, much to his chagrin, usually as "Hamsterwheel" or "Hamsterveal".
- Gantu (voiced by Kevin Michael Richardson) - Forcibly retired from his position as captain of the Galactic Armada at the end of the original film, he serves as Hämsterviel's henchman. He fights against Lilo and Stitch in capturing the experiments, but is usually defeated due to his arrogance, bad luck, and the abilities of Stitch.
- X-625/Reuben (voiced by Rob Paulsen) - Gantu's sidekick in capturing experiments, he is a genetic experiment who has all the abilities of Stitch (plus a greater fluency in English). However, he is a lazy coward who prefers to make sandwiches rather than fight. Although he is now known as "Reuben", he was not given this name until Leroy & Stitch, and was referred to by his experiment number throughout the series, although Lilo called him "Sandwich Boy" once in the episode "627".
Both the original air dates and production numbers do not reflect the actual continuity of the series. Many continuity errors, including many events involving the location and availability of certain experiments, take place later in the series:
- Episode 65 "Snafu" takes place before episode 40 "Spike" because Fibber and Nosy are rescued in "Snafu", but are already rescued in "Spike", and Bonnie and Clyde are still paroled. The same is true for Hammerface seen in episode 9 "The Asteroid".
Several episodes take place near or on holidays and special events:
- Episode 5 "Holio": Mertle's birthday.
- Episode 6 "Spooky": Halloween (October 31).
- Episode 12 "Amnesio": Lilo's birthday.
- Episode 19 "627": December. Pleakley made a second Thanksgiving feast because he thought it was once a month instead of once a year.
- Episode 21 "Topper": Christmas Eve (December 24).
- Episode 23 "Houdini": Mertle's "half-birthday" party (likely 6 months after her real birthday).
- Episode 31 "Remmy": The anniversary of the death of Lilo's parents.
- Episode 32 "Hunkahunka": Valentine's Day (February 14).
- Episode 46 "Checkers": The Merrie Monarch Festival (traditionally starting on Easter Sunday).
- Episode 47 "PJ": April Fools' Day (April 1)
- Episode 48 "Ploot": Earth Day (April 22).
A few crossover episodes featuring characters from other Disney animated shows were shown during the series' second season. Some of these characters include:
- Kim Possible, Ron Stoppable, Wade, Doctor Drakken, Shego and Rufus from the Disney series Kim Possible. Dr. Drakken kidnaps Stitch in order to clone him and deliver him to Dr. Hamsterviel. Jumba confuses Rufus with Experiment 607, which looks remarkably similar.
- Penny, Oscar, Trudy, BeBe, CeCe and Suga Mama Proud (and Puff the dog) - along with Wizard Kelly - from The Proud Family. In this episode, the Prouds are staying at "Jumba and Pleakley's Bed and Not Breakfast" on vacation. A rampaging experiment (Experiment 397 - "Spats") causes numerous characters to argue constantly.
- T.J. Detweiler, Vince LaSalle, Ashley Spinelli, Gretchen Grundler, Mikey Blumberg, Gus Griswald and Miss Muriel P. Finster from Recess. In this episode the Recess children are accompanying Gretchen to Hawaii when they are attacked by Experiment 285 - "Lax". Miss Finster, supposedly looking after the children, spends her time in the hotel salon.
- Several cast members from American Dragon: Jake Long including Jake Long, Luong Lao Shi, Fu Dog, Trixie Carter and Arthur "Spud" Spudinski. Jake is amongst a number of contestants in a skateboard competition - Lilo also takes part. Experiment 316 - "Morpholomew" - turns Lilo first into Keoni and then into Jake, after he is captured by Gantu (who thinks Jake is Experiment 316). Luong Lao Shi falls for Mrs. Hasagawa.
- The first season episode with Experiment 032 - "Fibber" - reunites the cast of the comedy series The Kids in the Hall. Actor Kevin McDonald, who plays Pleakley, is joined by the rest of the cast members who play his various family members, except for Dave Foley, although Foley does appear in the episode as well, playing a priest.
According to executive producer Jess Winfield, the crossover episodes were inspired by the four "Inter-Stitch-al" teaser trailers that were made for the original Lilo & Stitch film, which featured Stitch invading scenes in various Disney Renaissance films. Because of this, the crossover episodes heavily imply that each of the five Disney Channel Original cartoons take place in the same universe.
- Lilo & Stitch: The Series was originally going to be named Stitch! The Series. This decision was later changed, resulting in the mismatched title of its pilot, Stitch! The Movie. The title Stitch! (with the exclamation point) would later be used as the title of an anime series.
- In the episode "Finder", Yuki asks if Finder could find her Uncle Jimbo, a possible reference to Jimbo Kern from South Park.
- In the episode "Babyfier", Lilo wants to see a movie called Sludge Mummies II: Attack of the Bones, which may be an allusion to Star Wars Episode II - Attack of the Clones.
- Tokyopop has published three Lilo & Stitch Cine-manga books: The Search Begins (with the episodes "Poxy" and "Spooky"), Sparring and Charring ("Kixx" and "Cannonball"), and Contents Under Pressure ("Yin-Yang" and "Richter").
- Unlike the movies, Lilo often wears a green dress with flowers instead of the same design but red in the first season, though she wears the red one more often in the second season.
- Unlike other Disney Channel Original shows that premiere on Disney Channel then later come to ABC Kids, Lilo & Stitch premiered on ABC and then came to Disney Channel as a marathon on Columbus Day 2003.
- This is the third Disney Channel Original Series to end after two seasons, after Lizzie McGuire and The Proud Family.
- Stitch and Reuben are both proven to be ticklish in different episodes. Stitch is tickled by a growth ray in "Shortstuff", and Reuben is tickled by Tickle-Tummy in "Snafu".
- Cannonball and Gigi use powers in Leroy & Stitch that they never use in the series: Cannonball being able to roll into a ball and Gigi being able to talk.
- Characters from Lilo & Stitch: The Series appeared in a parody of the "We're All in This Together" scene from High School Musical titled "Stitch Meets High School Musical". The vignette appeared in the High School Musical: Around the World one-year anniversary special and can also be found on the Deluxe Dance Edition 2-disc DVD release of High School Musical 2.
- Parody musician "Weird Al" Yankovic makes a guest appearance in "Tank" as a wandering minstrel.
- One of the characters who debuted in this show (Splodyhead) was given a cameo in Big Hero 6 as one of the pillows on Fred's bed. This makes Lilo & Stitch: The Series the first Disney sequel TV series to be referenced in a Disney Animated Canon film.